1. Field of the Invention
The subject invention is directed to a low profile drive mechanism for the agitator shaft of a chemical reactor vessel which includes a removable shaft-seal cartridge.
2. Description of the Prior Art
U.S. Pat. No. 3,877,706 of L. L. Haas discloses, in FIG. 1 thereof, drive means for the agitator shaft of a reactor vessel which drive means must be substantially disassembled in order to obtain access to the shaft seal. A motor drive is mounted on the top and to one side of an elongate drive housing which extends upwardly from a mounting flange which defines an opening in the top of the vessel through which the upper end-adjacent portion of the agitator shaft projects. A housing for a removable shaft-seal-cartridge is secured relative to said mounting flange interiorly of the lower end of the drive housing wherein the overall height of the drive housing is six and one-half times the overall height of the seal housing.
A quill sleeve is rotatably mounted within the drive housing by means of a first thrust bearing adjacent the upper end of the sleeve and a second thrust bearing adjacent the lower end thereof.
An elongate quill shaft is disposed within the quill sleeve wherein the upper end of the quill shaft is bolted to the upper end of the quill sleeve and wherein the lower end of the quill shaft is provided with a tapered socket into which the complementary tapered end of the agitator shaft is received and disposed in driven relationship with the socket via a key.
The lower end of an elongate drawbar which is housed within the quill shaft is threaded into the upper end of the agitator shaft whereas the upper end thereof is threaded into an opening in a lock nut ring which rests upon the upper end of the quill shaft. Jack screws lift the lock nut relative to the quill shaft for drawing the tapered end of the agitator shaft into the tapered socket of the quill shaft.
In order to further insure the connection between the quill sleeve and the agitator shaft end a wedged collar and a wedged split adaptor ring are inserted into the annular space between the agitator shaft and quill sleeve below the lower end of the quill shaft, and screw means are provided for imparting relative movement to said collar and ring for securely anchoring the lower end of the quill sleeve relative to the lower bearings whereby the upper end of the agitator shaft is rotatably supported against radial thrust loads.
The aforesaid drive means cannot be disconnected or uncoupled from the agitator shaft until and unless the seal cartridge within the seal housing has been lifted out of its housing and slid upwardly along that portion of the agitator shaft between the lower end of the quill sleeve and the upper end of the seal housing, and until after a split plate is clamped about the agitator shaft at a location below the lower end of the having-been-raised seal cartridge.
The wedged split adaptor ring is then removed from the annular space below the quill shaft, and the wedged collar is lowered onto the upper end of the raised seal cartridge. The jack screws in the lock nut are actuated to lower the drawbar to loosen the connection between the tapered end of the actuator shaft and the drive socket of the quill shaft by forcing the agitator shaft downwardly a short distance until the split plate thereon engages the upper end of the seal housing. The lock nut is unscrewed from the upper end of the drawbar after which the upper end of the quill shaft is unbolted from the upper end of and then withdrawn upwardly through the outer quill sleeve thereby providing access to the interior of the quill sleeve.
Long bolts are then introduced into the quill sleeve and their lower ends are threaded into tapped holes in the collar resting on the upper end of the raised seal cartridge after which the bolts are raised to withdraw the collar upwardly through and out the upper end of the quill sleeve.
The long bolts are then reintroduced into the quill sleeve whereby to threadably engage the upper end of the seal cartridge which is then pulled upwardly through and out the upper end of said sleeve.
The upper end of the agitator shaft at all times projects upwardly into and in radially spaced relationship with the lower portion of the quill sleeve by an appreciable distance which is at least equal to the overall height of the housing of the seal cartridge whereby removal of the seal cartridge from the agitator shaft can only be accomplished by initially moving the cartridge upwardly along the agitator shaft and thence upwardly along and through the inside of the quill sleeve and over the drawbar which projects upwardly from the upper end of the agitator shaft within the quill sleeve.
From the foregoing it will be noted that considerable headroom space is required above the upper end of the elongate drive housing to provide access to and accommodate the length of the quill shaft and the long bolts which are inserted into the upper end of the quill sleeve as aforesaid.
U.S. Pat. No. 2,931,631 of E. S. Harrison discloses drive means for the upper portion of the agitator shaft of a reactor vessel wherein the shaft is provided with a mechanical seal located within an outer shell or housing having an upper flanged end which is bolted to a drive bearing on a drive shaft the lower end of which is disposed in radially spaced relationship with the interior of an axial line in the upper end of the agitator shaft, and a lower flanged end which is bolted to the flanged nozzle of a reactor vessel. Considerable head room above the drive bearing is required in order to effect sufficient disassembly of the drive mechanism to provide access to the sealing means which are secured, in circumscribing relationship with the outer surface of the end-adjacent portion of the agitator shaft. As clearly illustrated in FIG. 1 sufficient headroom is required to permit the withdrawal of the upper depending drive shaft by an amount sufficient to remove it from the axial bore in the drive bearing which is bolted to the upper flange of the seal housing and from the axial bore in the upper end of the agitator shaft. Thereafter the lower flange of the seal housing is disconnected from the flange nozzle of the vessel for enabling it and the drive bearing to be lifted upwardly off the sealing means on the upwardly projecting portion of the agitator shaft.
Alternatively, the lower flange of the seal housing can be disconnected from the flanged nozzle thereby permitting the seal housing, the drive bearing, and the upper drive shaft and its drive means to be lifted upwardly by an amount to provide access to the seal mechanism.
Another type of drive mechanism for the upper end of an agitator shaft which is provided with a seal cartridge utilizes a spacer spool of considerable length which is interposed between the lower surface of a drive coupling which is secured to and depends from the lower end of the depending drive shaft of a drive mechanism which is secured to and carried by an elongate motor housing the lower end of which is mounted relative to the nozzle flange of a reactor vessel.
Removal of the elongate spacer spool provides access to the seal without necessitating lifting of the drive mechanism, however the considerable spacing between the drive shaft and agitator shaft requires the use of a steady bearing in the seal cartridge which introduces additional alignment procedures in assembly.
To the best of applicants' knowledge the prior art drive mechanisms hereinabove referred to require headroom space above the mounting flange of the nozzle of a reactor vessel of from a minimum of four and one-half feet to something in excess of seven feet, in order to provide access to and permit the removal of the seal which circumscribes the upper end-adjacent portion of the agitator shaft of the vessel.